Reactor with antimicrobial medium for liquid disinfection

ABSTRACT

It has been discovered that providing a reactor for disinfecting liquids having therein an antimicrobial-coated medium in an active and dynamic suspension allows for the passage of certain particles while preventing the passage of viable microorganisms. There is provided a reactor for disinfecting a liquid comprising a raw liquid inlet for allowing a raw liquid to enter the reactor, a disinfected liquid outlet for releasing a disinfected liquid from the reactor, and a suspension device for creating a highly dynamic suspension of the antimicrobial medium in a cross-section of the reactor through which the raw liquid passes to insure a substantially uniform, high average number of interactions between the antimicrobial medium and microorganisms present in the liquid passing through the reactor, thereby decreasing a quantity of viable microorganisms in the liquid as it passes from the inlet to the outlet.

This application claims priority to U.S. Provisional Application No.61/756,199 filed Jan. 24, 2013.

FIELD OF THE INVENTION

The subject matter disclosed generally relates to reactors for liquiddisinfection. The subject matter disclosed relates more specifically toorganosilane coated particles for liquid disinfection.

BACKGROUND OF THE INVENTION

An ever increasing environmental concern associated with harmfulbacteria, and more particularly, with harmful bacteria in waterenvironments, has recently been observed.

For example, E. Coli is a widely recognized health risk and Legionellapneumophila is a known pathogen associated with cooling towers. The mostcommon sources of Legionella and Legionnaires' disease outbreaks arecooling towers (i.e., used in industrial cooling water systems),domestic hot water systems, and spas. Additional sources include largecentral air conditioning systems, fountains, domestic cold water,swimming pools (i.e., especially in Scandinavian countries and northernIreland) and similar disseminators that draw upon a public water supply.Natural sources include freshwater ponds and creeks. Many governmentalagencies, hospitals, long term health care facilities, retirement homes,cooling tower manufacturers, and industrial trade organizations havedeveloped design and maintenance guidelines for preventing orcontrolling the growth of Legionella in cooling towers, but also in hotpressure systems. More particularly, in retirement homes, the growth ofLegionella may be accelerated since the water needed from the hot watersystems must be at a lower temperature for well being of an elderlyperson.

Peterson et al. (U.S. patent application Ser. No. 10/820,121) andWilliamson et al. (U.S. patent application Ser. No. 11/593,750) teachfilters using solid phase carriers coated with quaternary ammoniumorganosilane coatings to reduce viable microorganisms as liquid passesthrough the filter. In these two applications, the coated filteringmedium is effectively “immobilized” or “stationary” in order to form anefficient filtering barrier.

SUMMARY OF THE INVENTION

It has been discovered that providing a reactor for liquid disinfectionhaving an antimicrobial-coated medium therein that is not immobilized ina filter but rather in an active and dynamic suspension in the reactorallows for the passage of certain particles while preventing the passageof viable microorganisms/microbes.

According to an embodiment, there is provided a reactor for disinfectinga liquid comprising, a raw liquid inlet for allowing a raw liquid toenter the reactor; a disinfected liquid outlet for releasing adisinfected liquid from the reactor; and a suspension device forcreating a highly dynamic suspension of an antimicrobial medium in across-section of the reactor through which the raw liquid passes toinsure a substantially uniform, high average number of interactionsbetween the antimicrobial medium and microorganisms present in theliquid passing through the reactor, thereby decreasing a quantity ofviable microorganisms in the liquid as it passes from the inlet to theoutlet. In such an embodiment a microorganism in the liquid passingthrough a channel of the antimicrobial suspension will make an averagenumber of efficient contacts (i.e. killing contacts) with theantimicrobial medium that is uniform for all possible channels in thereactor.

According to another embodiment, there is provided an inlet nozzleconnected to the raw liquid inlet, the nozzle being located below thedisinfected liquid outlet, such that an upstream flow in the reactorcauses the antimicrobial medium to be in suspension in the reactorduring operation. It will be appreciated that the predetermined upstreamflow rate required to provide an appropriate level of suspension(expansion) of the particles is a function of many parameters such asthe density, the expandability, the sphericity and roundness of theparticles to be put into suspension.

According to yet an embodiment, the suspension device comprises anagitator in the reactor, wherein in operation, the agitator agitates theantimicrobial medium and the raw liquid entering into the reactor. Thesuspension device can also comprise an air inlet for injecting an airstream into the reactor, thereby allowing the antimicrobial medium to bein suspension in the reactor during operation. It will be appreciatedthat the air inlet can be used either alone or in conjunction with othersuspension devices in order to provide the appropriate level ofexpansion of the antimicrobial medium.

According to still an embodiment, there is provided a filtering devicefor separating the antimicrobial medium from the liquid. The filteringdevice can comprise, for example, a nylon membrane and/or a wedgewire toprevent the outflow of antimicrobial medium from the reactor.

According to an embodiment, there is provided a media coated with anantimicrobial compound. The media can comprise one or any combination ofsand particles, anthracite, gravel, activated carbon, zeolite, clay,diatomaceous earth, garnet, ilmenite, zircon, charcoal, ion exchangeresin, silica gel, titania, black carbon, PVC, glass, glass, polymericparticles, plastic particles, organic particles. The media can comprisesand particles having an average particle size between 0.01 mm and 1.0mm. The media preferably comprise sand particles having an averageparticle size of approximately 0.15 mm.

According to another embodiment, there is provided an antimicrobialcompound comprising one or any combination of a zero-valent metalcompound, an iron compound, a cast iron compound, a high purity ironcompound, an iron sponge compound, iron powder, an aluminum compound, aferrous sulfate compound, a ferric chloride compound, an aluminumsulfate compound, a quaternary ammonium salt compound, a quaternaryammonium compound, an oxidizing agent, a chelating agent, a surfactant,a wetting agent, an antibiotic compound, an antifungal agent, anantiviral agent, a silver compound, a copper compound, a zinc compound,a zero-valent silver compound, a zero-valent copper compound, azero-valent zinc compound, a copper sulfate compound.

According to a preferred embodiment, the antimicrobial compound cancomprise octadecyldimethyl(trimethoxysilylpropyl) ammonium chloride.

According to yet another embodiment, the antimicrobial medium cancomprise media coated with a concentration of antimicrobial compoundbetween 0.1 to 1000 moles of compound per kilogram of media butpreferably approximately 15 moles of compound per kilogram of media.

According to still another embodiment, the antimicrobial medium is ableto resist (maintain its antimicrobial activity) to a 20 hour 0.1% bleachpre-treatment.

According to an embodiment, the antimicrobial medium is effective atkilling the bacterial strains E. coli ATCC8739, E. coli O157:H7 EDL933(the strain known to cause Hamburger disease) and Legionella pneumophila(often found in cooling towers).

According to another embodiment, a base is configured to support thereactor such that a longitudinal axis of the reactor is eitherhorizontal or vertical. According to yet another embodiment, a shape ofthe reactor can be a conical shape, a cylindrical shape, a square shape,a polygonal shape, a spherical shape.

According to still another embodiment, there is provided a secondarytank for allowing a separation between the antimicrobial medium and thedisinfected liquid flow. In such an embodiment, a secondaryantimicrobial medium inlet allows a separated antimicrobial medium tore-enter the reactor.

According to an embodiment, bearings can be provided for rotating thereactor such that, in operation, the reactor rotates about itslongitudinal axis, allowing the antimicrobial medium to be put intosuspension in the reactor.

According to another embodiment, the is provided a reactor comprising aplurality of compartments for receiving the antimicrobial mediumtherein.

According to yet another embodiment, the suspension device causes anexpansion of the antimicrobial medium by between 10% and 80% as comparedto when the suspension device is inactive. According to a preferredembodiment, the antimicrobial medium is expanded by approximately 50% ascompared to when the suspension device is inactive.

According to still another embodiment, a flow rate of approximately 15m³ of liquid per m² of surface area per hour entering the reactormaintains a 50% expansion of the antimicrobial medium of inside thereactor as compared to when there is an absence of flow.

According to an embodiment, a flow sensor and an expansion sensor isprovided for triggering at least one of an alarm and a flow adjustorwhen a detected flow rate or a level of expansion of the antimicrobialmedium is outside of a predetermined range for creating a level ofexpansion of the antimicrobial medium inside the reactor.

According to another embodiment, a cooling tower is combined with areactor according to the present invention and the liquid is liquid fromthe cooling tower.

According to an embodiment, there is provided a method of disinfecting aliquid containing microorganisms comprising, providing a reactor havinga liquid inlet, a liquid outlet, and an antimicrobial medium therein;receiving the liquid from the liquid inlet; creating a highly dynamicsuspension of the antimicrobial medium in a cross-section of thereactor, thereby causing a high average number of interactions betweenthe microorganisms and the antimicrobial medium and decreasing aquantity of viable microorganisms as the liquid passes from the inlet tothe liquid outlet; and releasing from the liquid outlet a disinfectedliquid separated from the antimicrobial medium.

According to an embodiment, it is advantageous to filter theantimicrobial medium from the liquid before releasing it.

According to an embodiment, there is provided a reactor for liquiddisinfection comprising: a tank; a raw liquid inlet on the tank forallowing a raw liquid flow to enter the tank; a disinfected liquidoutlet on the tank for allowing a disinfected liquid flow to exit thetank; and an antibacterial medium in the tank for contacting anddisinfecting the raw liquid flow; wherein when in operation, theantibacterial medium is in suspension in the tank and allows for thedisinfected liquid flow exiting the tank to have a lower bacteriaconcentration than the raw liquid flow entering the tank.

According to another embodiment, the raw liquid inlet is below thedisinfected liquid outlet for creating an upstream flow in the tank whenthe reactor is in operation, thereby allowing the antibacterial mediumto be in suspension in the tank.

According to a further embodiment, the reactor further comprises anagitator in the tank, wherein when in operation, the agitator agitatesthe raw liquid flow entered in the tank and the antibacterial medium.According to yet another embodiment, the antibacterial medium comprisesa media coated with an antibacterial compound.

According to yet another embodiment, the tank is one of: a closed tankand an opened tank. According to another embodiment, the tank definesone of: a longitudinal horizontal axis and a longitudinal vertical axis.

According to yet another embodiment, the reactor further comprises anair inlet at the bottom of the tank for allowing an air stream to enterthe tank when the reactor is in operation, thereby allowing theantibacterial medium to be in suspension in the tank.

According to a further embodiment, the media can comprise a PVCmaterial, a polyethylene material, a plastic material, a stainless steelmaterial, a steel material, a heat-resistant material, a cold-resistantmaterial and any combination thereof.

According to yet another embodiment, when in operation, the media coatedwith the antibacterial compound prevents bio-fouling.

Features and advantages of the subject matter hereof will become moreapparent in light of the following detailed description of selectedembodiments, as illustrated in the accompanying figures. As will berealized, the subject matter disclosed and claimed is capable ofmodifications in various respects, all without departing from the scopeof the claims. Accordingly, the drawings and the description are to beregarded as illustrative in nature, and not as restrictive and the fullscope of the subject matter is set forth in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present disclosure will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 illustrates a reactor with an antimicrobial medium in accordancewith an embodiment;

FIG. 2 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 3 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 4 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 5 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 6 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 7 illustrates a reactor with an antimicrobial medium in accordancewith another embodiment;

FIG. 8 is a cross sectional view of the reactor of FIG. 7;

FIG. 9 is a graph of bacterial activity as a function of variousantimicrobial coatings, highlighting mineral/metal based coatings (FIG.10A) and organic based coatings (FIG. 10B);

FIG. 10 is a graph of bacterial (E. coli—ATCC8739) activity as afunction of various antimicrobial coatings of sand having averageparticle sizes of 0.5 mm and 0.15 mm;

FIG. 11 is a graph of bacterial activity as a function of variousantimicrobial coatings in the presence or absence of bleachpretreatment;

FIG. 12 is a graph of bacterial (E. coli—O157:H7 EDL933) activity as afunction of various antimicrobial coatings of sand having averageparticle sizes of 0.5 mm and 0.15 mm;

FIG. 13 is a graph of bacterial (Legionella pneumophila) activity as afunction of various antimicrobial coatings of sand having averageparticle sizes of 0.5 mm and 0.15 mm;

FIG. 14 is a graph of bacterial (E. coli—ATCC8739) activity as afunction of various incubation times (between 5 and 60 minutes) withvarious antimicrobial-coated sand samples having a 0.5 mm averageparticle size; and

FIG. 15 is a graph of bacterial (E. coli—O157:H7 EDL933) activity as afunction of various incubation times (between 10 seconds and 8 minutes)with antimicrobial-coated sand having a 0.5 mm average particle size.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION

In embodiments there are disclosed reactors for liquid disinfection andcooling tower for liquid disinfection.

Referring now to the drawings, and more particularly to FIGS. 1-7, thereis shown a reactor 10 for liquid disinfection. The reactor 10 includes atank 11, a raw liquid inlet 12 on the tank 11 which allows a raw liquidflow (not shown) to enter the tank 11 and a disinfected liquid outlet 14on the tank 11 which allows a disinfected liquid flow (not shown) toexit the tank 11. The reactor 10 further includes an antimicrobialmedium 16 in the tank 11 which, in operation of the reactor 10, contactsand disinfects the raw liquid flow 12 which enters the tank 11 throughnozzle 29. As shown in FIGS. 1-7, in operation, the antimicrobial medium16 is in suspension in the tank 11. This configuration of theantimicrobial medium 16 suspended in the tank 11 allows the disinfectedliquid flow which exits the tank 11 to have a smaller bacteriaconcentration than the raw liquid flow which enters the tank 11.

According to an embodiment and referring now to FIGS. 1, 3 and 6, theraw liquid inlet 12 on the tank 11 of the reactor 10 is below thedisinfected liquid outlet 14 for creating an upstream flow (not shown)in the tank 11 when the reactor 10 is in operation. This configurationof the raw liquid inlet 12 and disinfected liquid outlet 14 allows theantimicrobial medium 16 to be in suspension in the tank 11 of thereactor 10. In some embodiments such as that shown in FIG. 1, anexpansion sensor 17 can detect a level of suspension (expansion) of theantimicrobial medium 16 in the tank. It will be appreciated that, insome cases, controlling a level of expansion of the antimicrobial medium16 in the reactor 10 can be advantageous for treating specific types ofraw liquids. In this case, an expansion sensor 17 detects the level ofexpansion of the antimicrobial medium 16 in the reactor 10 and, inresponse, a controller (shown in FIG. 3) can adjust certain parametersin order to return the level of expansion back into the predeterminedrange of optimal expansion levels. The level of expansion can bedetected by various sensors such as a turbidimeter, spectrometer, etc.In some embodiments, an expansion that is outside the predeterminedrange will trigger an alarm to alert an operator and/or to initiate anautomatic corrective response by the controller (e.g. adjusting a valveto control flow rate, adjusting agitator speed). It will be appreciatedthat an embodiment such as that shown in FIGS. 1,3 and 6 may require apump 27 (see FIG. 3) for creating the necessary force for upstream flowof the liquid against gravity and against an antimicrobial medium 16. Itwill also be appreciated that a positive displacement pump can be usedto insure sufficient flow rates responsible suspension of the mediawithout thereby requiring sensors/valves to ensure sufficient flow.

In some embodiments, as shown in FIG. 3, a media supporting element 13is located near a bottom of a tank to receive and support the mediapresent therein. The media supporting element 13 can be combined with anozzle configured to release a raw liquid at a plurality of locations atthe bottom of the tank (not shown) to avoid the creation of preferentialcurrent flows (channels) or to favor the full and complete suspension ofthe media inside the tank. The media supporting device can also be atype of wedgewire™ material that is able to support the media whileallowing the passage of raw liquid from the bottom of the tank. In someembodiments, especially embodiments designed for higher flow rates intothe tank, a media barrier 15 is placed above the antimicrobial medium 16to prevent the loss of medium as liquid flows out of the disinfectedliquid outlet 14. The media barrier 15 can be a nylon membrane coveringa cross-section of the reactor. In other embodiments, the media barrier15 can be a wedgewire-like material (e.g. made of stainless steel) andthe media supporting element 13 can be a nylon membrane. The mediabarrier 15 and media supporting element 13 can also be made from othermaterials such as Teflon®, polyethylene (PE), perfluoroalkoxy (PFA),polytetrafluoroethylene (PTFE), polypropylene (PP) or other plasticpolymers. It will be appreciated that a cross-section of the reactormeans a “slice” of reactor at some location between the inlet and theoutlet and as such, a slice of reactor can be generally orthogonal tothe axis defined by the inlet and the outlet. A membrane covering acomplete cross-section of the reactor would not allow raw liquid to passfrom the inlet to the outlet without traversing the membrane and wouldtherefore capture all possible “channels” from the inlet to the outletat one particular location.

It will be appreciated that, in some embodiments such as that shown inFIG. 3, a controller 23 receives information from sensors about certainparameters/characteristics of the raw liquid (e.g. flow sensor 25 atliquid outlet 14) and adapts treatment accordingly. For example, ahigher bacterial concentration or a specific bacteria type can betreated more effectively by adapting the flow rate of liquid into andout of the reactor or by creating a more active “suspension”. Othertypes of information that can be provided by sensors include, but arenot limited to pH, TSS (total suspended solids), volume to be treated,redox potential. Upon processing input received from the sensors, thecontroller/processor can adapt treatment, such as controlling the flowrate of liquid into the reactor using a valve 19, the forcefulness ofsuspension of the antimicrobial medium, the residence time ortemperature inside the reactor, etc. For example, if the controller 23receives information from the reactor 10 that a flow rate determined bya flow sensor 25 in the liquid outlet 14 not be sufficient for keeping adesired level of expansion of the antimicrobial medium 16 in thereactor, an alarm 21 can be activated in order to alert an operator orto automatically initiate a response, such as the adjustment of valve 19for controlling flow rate into the reactor in a desired predeterminedrange. It will be appreciated that if the desired level of expansion isachieved, the level of activity of the medium may be insufficient tokill/neutralize the microorganisms.

According to another embodiment and referring now to FIGS. 2 and 4, thereactor 10 may further includes an agitator 18 in the tank 11. Inoperation of the reactor 10, the agitator 18 agitates the raw liquidflow entered in the tank 11 by the raw liquid inlet 12 and theantimicrobial medium 16. This addition of the agitator 18 in the tank 11induces the antimicrobial medium 16 to be in suspension in the tank 11via a mechanical agitation process. Other suitable mechanical processesmay be utilized in this case.

The antimicrobial medium 16 in the tank 11 of the reactor 10 comprises amedia coated with an antimicrobial compound. The media may be, withoutlimitation, sand particles, anthracite particles, gravel particles,activated carbon particles, zeolite particles, clay particles,diatomaceous earth particles, garnet particles, ilmenite particles,zircon particles, charcoal particles, ion exchange resin particles,silica gel particles, titania particles, black carbon particles, PVC,glass, glass, polymeric particles, plastic particles, organic particlesand any suitable particles capable of being coated. The antimicrobialcompound coating the media may be, without limitation, a zerovalentmetal compound, an iron compound, a cast iron compound, a high purityiron compound, an iron sponge compound, iron powder, an aluminumcompound, a ferrous sulfate compound, a ferric chloride compound, analuminum sulfate compound, a quaternary ammonium salt compound, anorganosilane quaternary compound, a quaternary ammonium compound, anoxidizing agent, a chelating agent, a surfactant, a wetting agent, anantibiotic compound, an antifungal agent, an antiviral agent, a silvercompound, a copper compound, a zinc compound, a zero-valent silvercompound, a zero-valent copper compound, a zero-valent zinc compound, acopper sulfate compound and any suitable combination. It is to be notedthat the media (i.e., the sand particles) need to be very small forincreasing the possible surface of contact of the antimicrobial medium16 which will come into contact with the raw liquid flow.

According to another embodiment and referring now to FIGS. 1, 3, 5, 6and 7, the tank 11 of the reactor 10 is a closed tank 11.

According to another embodiment and referring now to FIGS. 2 and 4, thetank 11 of the reactor is an opened tank 11. It is to be noted that thecurved arrow presented on FIG. 4 between the tank 11 and the secondarytank 24 illustrates the flow consisting of water and antimicrobialmedium that can be transported from the tank 11 and the secondary tank24. This configuration of the tank 11 and the secondary tank 24 mayprovide for a better separation process.

According to another embodiment, the tank 11 of the reactor 10 maydefine, without limitation, one of a longitudinal horizontal axis and alongitudinal vertical axis. For example, FIGS. 1, 2, 3, 4 and 6 define atank 11 of the reactor 10 with a longitudinal vertical axis 22. However,FIGS. 5 and 7 define a tank 11 of the reactor 10 with a longitudinalhorizontal axis 20. Additionally, the tank 11 of the reactor 10 mayinclude, without limitation, one of a conical shape (FIGS. 1 and 2), acylindrical shape (FIGS. 2, 3, 4, 5, 6 and 7), a square shape, apolygonal shape, a spherical shape (bottom and top of the tank 11 ofFIGS. 3 and 6; left side and right side of the tank 11 of FIGS. 5 and 6)and any other suitable combination.

According to another embodiment and referring now to FIGS. 2 and 4, thereactor 10 may further includes a secondary tank 24 which allows aseparation process occurring between the antimicrobial medium 16 and thedisinfected liquid flow (not shown) (i.e., a flow of antimicrobialmedium mixed with a flow of disinfected liquid enters the secondary tank24 and a flow of antimicrobial medium exits the secondary tank 24 topossibly enter the tank 11+a flow of disinfected liquid exits thesecondary tank 24). Thus, the reactor 10 as described above may furtherinclude a secondary antimicrobial medium inlet 26 which allows anantimicrobial medium flow (not shown) to enter the tank 11 (i.e., thissecondary antimicrobial medium inlet 26 allows for recuperation of theantimicrobial medium 16).

According to another embodiment and referring now to FIGS. 5 and 7, thetank 11 of the reactor 10 may be a rotatable tank 11. According to thisembodiment, in operation, the rotatable tank 11 is capable of rotatingabout the longitudinal horizontal axis 20 which allows the antimicrobialmedium 16 to be in suspension in the tank 11 of the reactor 10. It is tobe noted that the reactor 10 as shown in FIG. 5 includes a worm drive 32for allowing the displacement of the antimicrobial medium 16 in the tank11 of the reactor 10.

According to another embodiment and referring now to FIG. 6, the reactor10 further includes an air inlet 28 at the bottom of the tank 11. Theair inlet 28 allows an air stream to enter the tank 11 when the reactor10 is in operation. The addition of the air inlet 28 on the tank 11allows the antimicrobial medium 16 to be in suspension in the tank 11.The reactor 10 further comprises a base 31 which allows the reactor tohave a longitudinal axis that is vertical in the embodiment of FIG. 6but horizontal (not shown) in the case of FIG. 7.

According to another embodiment and referring now to FIGS. 7-8, thereactor 10 further includes a plurality of compartments 30 in the tank11 for receiving the antimicrobial medium 16. In the reactor 10 shown inFIGS. 7-8, the configuration of the tank 11 and its plurality ofcompartments 30 allow the antimicrobial medium 16 to be in displacementand therefore improve the surface contact between the raw liquid flow inthe tank 11 to be disinfected and the antimicrobial medium 16.

FIG. 9 shows the number of living bacteria (as evaluated by the numberof CFUs/ml) which is indicative of the antibacterial activity of thevarious mineral and organic coatings tested. The objective of this setof experiments was to identify antibacterial coatings that performedwell in “suspension” as opposed to immobilized coatings in a sandfiltering apparatus, for example. Antimicrobial performance insuspension could not be predicted based on known antimicrobial activityof the immobilized coatings. The “T0” column of FIGS. 9A and 9Brepresents the initial microbial activity (CFUs/ml) before contactingany coated antimicrobial material (in this case, sand). NT is the“Non-Treated” negative control where the material was not coated withany antimicrobial product prior to contacting with the bacterialsolution. #7 and #70 are positive controls known in the art to provideantimicrobial activity. M1 to M4 (FIG. 9A) and OS1 to OS4 (FIG. 9B) arevarious types of mineral/metal coatings and organosilane coatings,respectively. OS1 is octadecyldimethyl (trimethoxysilylpropyl)ammoniumchloride (C₂₆H₅₈CINO₃Si) and is also identified as octadecyl TMACl orCAS# 27668-52-6. OS2 is the second organosilane molecule TMABr; OS3 isTMACl; and OS4 is polyethylene Imine. M1 comprises a Silver-basedantimicrobial; M2 comprises a Copper-based antimicrobial; M3 comprises aZinc-based antimicrobial; and M4 comprises a Copper and Zinc basedantimicrobial.

In the experiments shown in FIG. 9, the strain of bacteria used was E.coli O157:H7 EDL933. 2 grams of antimicrobial medium was incubated in 2ml solution for 10 minutes at 400 rpm on an orbital shaker. The liquidportion was then extracted to a agar plate, incubated at 37C for apredetermined period and the CFUs counted. None of the metal/mineralbased antimicrobial coating (M1 to M4) showed a significant commerciallyviable antimicrobial effect under the conditions tested. As seen in FIG.9B, one of the organic coatings (OS1) provided a very significantantimicrobial effect that was more potent than all the others, includingthe positive controls (#7 and #70).

Antimicrobial medium was initially prepared by mixing sand particles ofvarying diameter with antimicrobial solutions at differentconcentrations. FIG. 10 shows antimicrobial activity of variousOS1-coated sand particles of 0.5 mm and 0.15 mm on ATCC8739 strain of E.coli. Samples with different coating concentrations of organosilaneswere tested in order to determine optimal ranges. For example, insamples #1-5, the OS1 antimicrobial solution (at 5% dilution) was usedat a concentration of 250, 125, 90, 70 and 52.5 ml of organosilanesolution per kg of 0.5 mm sand, respectively. In samples #6-10, theantimicrobial solution (at 5% dilution) was used at a concentration of330, 160, 115, 87.5 and 62.5 ml of organosilane solution per kg of 0.15mm sand, respectively.

In the experiments shown in FIG. 11, 2 grams of antimicrobial medium(coated sand was incubated in 2 ml solution for 30 minutes at 400 rpm onan orbital shaker. The liquid portion was then extracted to an agarplate, incubated at 37C for a predetermined period and the CFUs counted.Samples #40 and #70 are positive controls using antimicrobial coatingsknown to be effective in immobilized conditions. Results showed that forall coating densities, the sand particles of 0.15 mm had betterantimicrobial activity than those of 0.5 mm. Samples #6 and #7 were themost promising because they achieved an antimicrobial activity similarto samples #8 and #9 which have higher coating densities.

Further testing was therefore performed on the OS1 coating of sandhaving particle sizes of 0.5 mm (#1 and #3) and 0.15 mm (#6 and #8)using the ATCC8739 strain of E. coli. FIG. 11 shows the resistance ofvarious concentrations of the OS1 coating to a 20 hour bleach/sodiumhypochlorite (0.1%) pre-treatment. In the experiments shown in FIG. 10,the 2 grams of the antimicrobial medium (coated sand) was incubated in 2ml solution for 30 minutes at 400 rpm on an orbital shaker. The liquidportion was then extracted to an agar plate, incubated at 37C for apredetermined period and the CFUs counted. Results show that bleachpre-treatment was able to “destroy” antimicrobial activity of certainsamples, most likely by oxidative processes. For example, althoughsample #1 showed very interesting antimicrobial activity, bleachpre-treatment essentially eliminated its subsequent antimicrobialactivity, making the efficacy of sample #1 doubtful for applications inoxidizing environments. On the other hand, the antimicrobial activity ofsample #6 was not affected by bleach pre-treatment, suggestinginteresting characteristics for this sample. The other samples tested(#3 and #8) showed a decrease in ant-microbial activity following bleachpretreatment

FIG. 12 shows antimicrobial activity of various OS1-coated sandparticles of 0.5 mm and 0.15 mm on O157:H7 EDL933 strain of E. coli.Samples with different coating densities of organosilanes were tested inorder to determine optimal coating density ranges. In the experimentsshown in FIG. 12, 2 grams of antimicrobial medium (coated sand) wasincubated in 2 ml solution for 30 minutes at 400 rpm on an orbitalshaker. The liquid portion was then extracted to an agar plate,incubated at 37C for a predetermined period and the CFUs counted.Samples #40 and #70 are positive controls using antimicrobial coatingsknown to be effective in immobilized conditions. Results showed that forall coating densities, the sand particles of 0.15 mm had betterantimicrobial activity than those of 0.5 mm. Sample #7 was promisingbecause it achieved antimicrobial activity similar to sample #6 with a50% lower concentration of antimicrobial. Samples #8-10 showed aconcentration dependent decrease in antimicrobial activity.

FIG. 13 shows antimicrobial activity of various OS1-coated sandparticles of 0.5 mm and 0.15 mm on Legionella pneumophila. Samples withdifferent coating densities of organosilanes were tested in order todetermine optimal coating density ranges. In the experiments shown inFIG. 12, 2 grams of antimicrobial medium (coated sand) was incubated in2 ml solution for 30 minutes at 400 rpm on an orbital shaker. The liquidportion was then extracted to an agar plate, incubated at 37C for apredetermined period and the CFUs counted. Samples #40 and #70 arepositive controls using antimicrobial coatings known to be effective inimmobilized conditions. Results showed that sample 7 (sand particles of0.15 mm) had better antimicrobial activity than sample #1 (sandparticles of 0.5 mm).

FIG. 14 shows results obtained with coated sand samples exposed forvarious times to the bacterial solution containing the ATCC8739 strainof E. coli. The first column for each set represents a contact time of 1hour, the second column is a 30 minute contact time, the third column isa 15 minute contact time and the fourth column is a 5 minute contacttime. FIG. 14 shows antimicrobial activity of various OS1-coated sandparticles (0.5 mm) using the ATCC8739 strain of E. coli. Samples withdifferent coating densities and contact times were tested in order todetermine optimal ranges for coating density and contact times. In theexperiments shown in FIG. 14, 2 grams of sand were coated with thevarious antimicrobial material and incubated in 2 ml solution for 30minutes at 400 rpm on an orbital shaker. The liquid portion was thenextracted to an agar plate, incubated at 37C for a predetermined periodand the CFUs counted. Samples “No Sand” and “NT” (non-treated/coatedsand) were negative controls while sample #40 was a positive controlusing antimicrobial coatings known to be effective in immobilizedconditions. Results showed that sample #1 had the best antimicrobialactivity of all samples tested.

FIG. 15 is a graph of bacterial (E. coli—O157:H7 EDL933) activity as afunction of various incubation times (between 10 seconds and 8 minutes)with antimicrobial medium (coated sand—OS1) having a 0.5 mm averageparticle size. In the experimental protocol, although a 1:1 ratio wasmaintained, a larger quantity of antimicrobial medium (250 g) and alarger volume of solution (250 ml) were used as compared to otherprotocols using mainly a 2 ml solution. The objective was to perform atime-course analysis in a range less than 5 minutes because the majorityof the antibacterial effect was already observed after a 5 minutecontact time, as shown in FIG. 14. In conclusion, because even theshortest contact time of 10 seconds showed a decrease in bacterial CFUsfrom more than 10⁶ CFUs/ml to less than 10¹ CFUs/ml, these resultssuggest that in the experimental conditions tested (higher volume andcoated sand quantity), the time-course analysis will have to use smallercontact times. Furthermore, because the antibacterial effect of theOS1-coated sand particles is significantly increased by an increasedvolume and quantity of sand, it is therefore possible that furtherincreasing from bench scale to industrial scale may provide even betterresults than those observed herein.

It will be understood that the microbial portion of the termantimicrobial includes all types of microbes/microorganisms such asbacteria, virus, fungi, mold, algae, yeast, protozoa. Thus, in someembodiments, the antimicrobial medium is an antibacterial medium.

It will be understood that operation of a reactor according to thepresent invention means treatment of raw liquid to decrease the numberof viable microorganisms from the raw liquid while an antimicrobialmedium is in suspension in the reactor.

It will be understood that putting the antimicrobial medium intosuspension inside the reactor using the suspension device creates acloud of particles that contacts microorganisms as they pass from theinlet to the outlet. Several factors can affect the number of efficientcontacts between particles and microorganisms. An efficient contact isunderstood to be a contact that will result in killing a microorganism,such as a bacteria. The mechanism by which antimicrobial compounds, suchas organosilane compounds kill microorganisms is known in the art whencoating immobilized media or surfaces, however, the efficiency andaction of organosilane compounds in a dynamic environment were notknown.

The flow of liquid entering the reactor from a liquid inlet at thebottom of the reactor acts as a “suspension device” and can determinethe efficiency of killing. For example, a high flow will cause a greaterexpansion of the antimicrobial medium and therefore a lower density suchthat efficient contacts may decrease. In addition, when no media barrier15 is present, a very high flow rate may cause a rapid loss ofantimicrobial particles from the reactor.

The size, sphericity and roundness of the particles will also affect theability of a predetermined inflow to cause an expansion of theantimicrobial medium. It is understood that a greater flow is requiredto expand highly spherical and round particles due to the lower frictionfrom the particles.

It will be appreciated that, when the reactor is shaped as an Imhoffcone and has a liquid inlet at the bottom of the reactor, a uniformsuspension will be observed at each cross-section of the cone/reactoralong its longitudinal axis (a vertical axis in this embodiment).However, a cross-section closer to the bottom of the cone/reactor mayprovide a level of suspension (i.e. activity, motion, energy) of theantimicrobial medium that is more or less dynamic than a level ofsuspension at a cross-section that is at a higher location of thecone/reactor. Overall however, the average number of effective contactsbetween antimicrobial medium and microorganism will nevertheless besimilar.

While preferred embodiments have been described above and illustrated inthe accompanying drawings, it will be evident to those skilled in theart that modifications may be made without departing from thisdisclosure. Such modifications are considered as possible variantscomprised in the scope of the disclosure.

1. A reactor for disinfecting a liquid comprising: a raw liquid inletfor allowing a raw liquid to enter the reactor; a disinfected liquidoutlet for releasing a disinfected liquid from the reactor; a suspensiondevice for creating a highly dynamic suspension of an antimicrobialmedium in a cross-section of the reactor through which the raw liquidpasses to insure a substantially uniform, high average number ofinteractions between the antimicrobial medium and microorganisms presentin the liquid, thereby decreasing a quantity of viable microorganisms inthe liquid as it passes from the inlet to the outlet; and an inletnozzle connected to the raw liquid inlet, said nozzle being locatedbelow the disinfected liquid outlet, such that an upstream flow in thereactor causes the antimicrobial medium to be in suspension in thereactor during operation.
 2. (canceled)
 3. The reactor of claim 1,wherein the suspension device further comprises an agitator in thereactor, wherein in operation, the agitator agitates the antimicrobialmedium and raw liquid entering into the reactor.
 4. The reactor of claim1, wherein the suspension device further comprises an air inlet forinjecting an air stream into the reactor, thereby allowing theantimicrobial medium to be in suspension in the reactor duringoperation.
 5. The reactor of claim 1, further comprising a filteringdevice for separating the antimicrobial medium from the liquid.
 6. Thereactor of claim 5, wherein the filtering device comprises one or moreof a nylon membrane and a wedgewire.
 7. The reactor of claim 1, furthercomprising a quantity of said antimicrobial medium, wherein theantimicrobial medium comprises a media coated with an antimicrobialcompound.
 8. The reactor of claim 7, wherein the media comprises one orany combination of sand particles, anthracite, gravel, activated carbon,zeolite, clay, diatomaceous earth, garnet, ilmenite, zircon, charcoal,ion exchange resin, silica gel, titania, black carbon, PVC, glass,glass, polymeric particles, plastic particles, organic particles.
 9. Thereactor of claim 8, wherein the media comprises sand particles having anaverage particle size between 0.01 mm and 1.0 mm.
 10. The reactor ofclaim 8, wherein the media comprises sand particles having an averageparticle size of approximately 0.15 mm.
 11. The reactor of claim 7,wherein the antimicrobial compound comprises one or any combination of azero-valent metal compound, an iron compound, a cast iron compound, ahigh purity iron compound, an iron sponge compound, iron powder, analuminum compound, a ferrous sulfate compound, a ferric chloridecompound, an aluminum sulfate compound, a quaternary ammonium saltcompound, a quaternary ammonium compound, an oxidizing agent, achelating agent, a surfactant, a wetting agent, an antibiotic compound,an antifungal agent, an antiviral agent, a silver compound, a coppercompound, a zinc compound, a zero-valent silver compound, a zero-valentcopper compound, a zero-valent zinc compound, a copper sulfate compound.12. The reactor of claim 7, wherein said antimicrobial compoundcomprises a quaternary organosilane.
 13. The reactor of claim 12,wherein said quaternary organosilane compound isoctadecyldimethyl(trimethoxysilylpropyl)ammonium chloride.
 14. Thereactor of claim 13, wherein said antimicrobial medium comprises mediacoated with a concentration between 0.1 to 1000 moles of compound perkilogram of media.
 15. The reactor of claim 13, wherein saidantimicrobial medium comprises media coated with a concentration ofapproximately 15 moles of compound per kilogram of media.
 16. Thereactor of claim 1, further comprising a quantity of said antimicrobialmedium, wherein said antimicrobial medium is resistant to a 20 hour 0.1%bleach pre-treatment.
 17. The reactor of claim 1, further comprising aquantity of said antimicrobial medium, wherein said antimicrobial mediumis effective at killing one or more of the bacterial strains E. coliATCC8739, E. coli O157:H7 EDL933 and Legionella pneumophila.
 18. Thereactor of claim 1, further comprising a base configured to support saidreactor such that a longitudinal axis of the reactor is one of ahorizontal axis and a vertical axis.
 19. The reactor of claim 1, whereina shape of the reactor comprises one or any combination of: a conicalshape, a cylindrical shape, a square shape, a polygonal shape, aspherical shape.
 20. The reactor of claim 1, further comprising asecondary tank for allowing a separation between the antimicrobialmedium and the disinfected liquid flow.
 21. The reactor of claim 1,further comprising a secondary antimicrobial medium inlet for allowingan antimicrobial medium to enter the reactor.
 22. The reactor of claim1, further comprising bearings for rotating the reactor such that, inoperation, the reactor rotates about the longitudinal axis, allowing theantimicrobial medium to be in suspension in the reactor.
 23. The reactorof claim 1, further comprising a plurality of compartments for receivingthe antimicrobial medium therein.
 24. The reactor of claim 1, whereinthe suspension device causes an expansion of the antimicrobial medium bybetween 10% and 80% as compared to when the suspension device isinactive.
 25. The reactor of claim 1, wherein the suspension devicecauses an expansion of the antimicrobial medium by approximately 50% ascompared to when the suspension device is inactive.
 26. The reactor ofclaim 1, wherein a flow rate of 15 m3 of liquid per m2 of surface areaper hour maintains a 50% expansion of the antimicrobial medium of insidethe reactor as compared to when a flow rate is zero.
 27. The reactor ofclaim 1, further comprising at least one of a flow sensor and anexpansion sensor that send data to a controller for triggering at leastone of an alarm and a flow adjustor when a detected flow rate or a levelof expansion of said antimicrobials media is out of a predeterminedrange for creating a level of expansion of said antimicrobial mediuminside said reactor.
 28. A cooling tower combined with a reactor ofclaim 1, wherein said liquid is from the cooling tower. 29-44.(canceled)